1. Field of the Invention
The present invention generally relates to an image processing apparatus for processing image data. More specifically, the present invention is directed to an image processing apparatus capable of synthesizing a plurality of image data based upon transmittance data, depth value data, or attribute data, set to these image data.
2. Description of the Related Art
Conventionally, synthesizing techniques for synthesizing two sets of images have been proposed in the field. For instance, a so-called "blue back cutting method" used in the television field is known in the art. This "blue back cutting method" will now be summarized with reference to FIG. 23 to FIG. 27.
An image "1" shown in FIG. 23 is an image to be synthesized. As represented in FIG. 24, a hatched image portion "2" is derived from this image 1 by using a certain image processing technique known in the field. This hatched image portion 2 is defined by eliminating a rectangular image from the image 1. Then, this image portion 2 is uniformly rewritten by blue color, so that such an image 3 as indicated in FIG. 25 is formed from the image 1 shown in FIG. 23. In other words, in the image 3 shown in FIG. 25, an image portion other than the rectangular image is uniformly painted in blue color.
In the case that the image 3 indicated in FIG. 25 is synthesized with, for example, another image "4" which will constitute a background containing another rectangular figure as represented in FIG. 26, the following synthesizing process is carried out. That is, as to the blue-colored dot (pixel) portion of the image 3, the image 4 for constituting the above-explained background is used, whereas as to other portions of this image 3, the image 3 is utilized. As a consequence, as illustrated in FIG. 27, the rectangular image can be inserted into the image 4 shown FIG. 26, which constitutes the background.
However, in the above-described conventional image synthesizing method, such a specific image containing a blue-colored background image must be prepared. In this case, this blue-colored image could not be used except for the image synthesizing process, and therefore the use of this blue-colored image is limited only to the specific purpose. Also, when the plural images are synthesized with each other, since these plural images are merely inserted into the image portions other than the blue-colored image, there is a certain limitation in representations of the resulting synthesized image. That is, there is a narrow width representing the synthesized image. For instance, when images to be synthesized with each other are entirely opaque, there is no representation limitation. To the contrary, when an image containing such a transparent portion as a window, e.g., an image of an automobile, a background image can be originally observed through the window of this automobile. However, the conventional image synthesizing method can not represent such an image.
Moreover, when a plurality of images are synthesized with each other, these images can not be overlapped with each other, such images may represent expanding atmospheres along the depth direction to observers in the conventional image synthesizing method. As a consequence, when such an image is formed using the conventional image synthesizing method, a single image is subdivided into plural images, and the specific image exclusively used in the image synthesization must be formed, resulting in cumbersome processing operations.